Device for molding ophthalmic lens material and method of molding therewith

ABSTRACT

A device comprises a lower die  6  composed of a lower die base portion and a lower die columnar portion of which tip surface is formed with a lower die molding surface corresponding to one surface of an ocular lens material; an upper die  8  composed of an upper die base portion that is fitted into an upper portion of a hollow hole of the cylindrical main body for parting the hollow hole into two, forming an intermediate chamber  18  between itself and the lower die base portion into which the monomer composition is filled, and forming an exterior accumulating chamber  20  on a side of an upper aperture of the hollow hole into which the monomer composition is accumulated, and an upper die columnar portion of which tip surface is formed with an upper die molding surface corresponding to another surface of the ocular lens material, wherein a molding cavity  22  having a communicating portion  24  is formed between the upper die molding surface and the lower die molding surface; and not less than three piercing holes  16  provided as to pierce the upper die base portion of the upper die in a vertical direction and as to be positioned at equal intervals around the upper die columnar portion. Simplification of the die arrangement of the molding device for molding ocular lens materials through polymerization in a mold can be effectively achieved, and superior transcriptability and uniform lens shape can be realized.

TECHNICAL FIELD

The present invention relates to a device for molding ocular lensmaterial and a molding method employing the same. More particularly, thepresent invention relates to a device for molding ocular lenses such asintraocular lenses or contact lenses or for molding ocular lens materialof shapes corresponding to precursors thereof by polymerizing monomercompositions for providing polymer products constituting these articleswithin a molding cavity, and it also relates to a method for moldingtargeted ocular lens material by performing polymerizing of specifiedmonomer compositions within the molding cavity by employing the abovedevice.

BACKGROUND ART

It has been conventionally known that ocular lenses such as intraocularlenses or contact lenses as well as ocular lens material of shapescorresponding to precursor thereof might be formed through variousmethods such as mechanical processing such as cutting or grindingmaterials of polymer products constituting these articles havingspecified shapes (rod-like bodies, blocks, etc.). Alternatively, theymight be formed through so-called mold polymerization in which monomercompositions providing polymer products are polymerized within a moldingcavity of a specified molding device (molding dies) to obtain a moldedarticle having a shape corresponding to the molding cavity.

Japanese Unexamined Patent Publication No. 52168/1995 discloses oneexample for obtaining targeted ocular lens material through such a moldpolymerization method. As shown in FIGS. 1 to 3, this publicationdiscloses a method for obtaining ocular lens material of polymerproducts by immersing molding dies composed of an upper die and a lowerdie within a monomer solution accumulated in a vessel and bypolymerizing the monomer solution within a molding cavity formed betweenthe upper die and the lower die through a radiant flux introducedthrough the upper die, thereby obtaining ocular lens material of polymerproduct corresponding to the shape of the molding cavity. In thisinvention, the upper die needs to be reliably shielded such that leakageof radiant flux that is passed through the upper die does not occur soas to prevent polymerization of monomer solution being present in theperiphery of the molding dies, and the upper die needs to be detachedfrom the lower die after the polymerization. Such various devises asexplained above that need to be taken various designs for the moldingdies result in a difficult die arrangement. Additionally, since moldedocular lens material need to be taken out from the monomer solutionafter the polymerization, residues of such monomers need to be removedfrom the ocular lens material wherein such operations might be quitetroublesome. Still further, one or more of monomers might volatilizefrom the monomer solution residing in the periphery of the molding diesat the time of polymerization, whereby variations in the composition ofthe monomer solution and thus in the composition of the obtained ocularlens material would be caused.

Further, the method and device for manufacturing optical lenses asdisclosed in Japanese Unexamined Patent Publication No. 256658/1995employs dies for molding that can be repetitively utilized whereineither one of two mold halves (half dies) is made to be moveable like apiston and wherein a specified molding cavity is formed between the twomold halves. In order to obtain targeted contact lenses (opticallenses), the molding cavity is filled with the monomer compositionwherein air within the molding cavity is eliminated while injecting aspecified monomer composition into the molding cavity formed between thetwo mold halves by means of, for instance, an injecting nozzle, forpolymerization. Also in this method, the arrangement of a movingmechanism for one of the mold halves and an injection mechanism formonomer solution makes the die arrangement complicated. Further,shrinkage accompanying the polymerization of monomer solution within themolding cavity would be difficult to be effectively compensated since acapacity of a flow outlet at which the injected monomer solution issubstantially resident is insufficient, and consequently, theflowability of the monomer solution within the molding cavity becomespoor so that the shapes of obtained contact lenses might not be uniform.In other words, supply of monomer solution to the molding cavityinterior, that is, the molding surfaces, becomes insufficient so thatunevenness of surfaces of obtained molded articles (contact lenses)might be caused, resulting in failure of targeted lens surfaces.

The present invention has been made in view of such circumstances, andits subject for solution lies in the point to achieve simplification ofdie arrangement in a device for molding ocular lens material throughmold polymerization, to improve the flowability of monomer compositionsof the ocular lens components at the time of polymerization shrinkage,and to make surfaces of the obtained ocular lens materials uniform byimproving the transcriptability of the molding cavity interior (moldingsurface) through supplying ocular lens components to the molding cavityin an uniform manner.

DISCLOSURE OF THE INVENTION

In order to solve such problems, the present invention provides a devicefor molding ocular lens material which is (a) a device for moldingocular lens or ocular lens material of shapes corresponding toprecursors thereof by polymerizing liquid monomer composition of polymerproducts constituting these articles within a molding cavity,characterized in that it comprises (b) a cylindrical main body having ahollow hole in which the monomer composition is accumulated, (c) a lowerdie composed of a lower die base portion disposed in a lower portion ofthe hollow hole as to close a lower aperture of the hollow hole of thecylindrical main body, and a lower die columnar portion that is erectedas to extent upward from an upper surface of the lower die base portionwithin the hollow hole and of which tip surface is formed with a lowerdie molding surface corresponding to one surface of the ocular lensmaterial, wherein a periphery of the lower die columnar portion isspaced, (d) an upper die composed of a plate-like upper die base portionthat is fitted into an upper portion of the hollow hole of thecylindrical main body for parting the hollow hole into two, forming anintermediate chamber between itself and the lower die base portion ofthe lower die into which the monomer composition is filled, and formingan exterior accumulating chamber on a side of an upper aperture of thehollow hole into which the monomer composition is accumulated, and anupper die columnar portion that is erected as to extent downward from alower surface of the upper die base portion within the hollow hole andof which tip surface is formed with an upper die molding surfacecorresponding to another surface of the ocular lens material, wherein aperiphery of the upper die columnar portion is spaced, wherein themolding cavity is formed between the upper die molding surface of theupper die columnar portion and the lower die molding surface of thelower die columnar portion, and wherein a communicating portion isformed over a whole circumferential of an exterior circumferentialportion of the molding cavity through which the monomer composition isintroduced from the intermediate chamber to the molding cavity, and (e)not less than three piercing holes for introducing the monomercomposition from the external accumulating chamber to the intermediatechamber that are provided as to pierce the upper die base portion of theupper die in a vertical direction and as to be positioned at equalintervals around the upper die columnar portion.

In the device for molding ocular lens material according to the presentinvention, the monomer composition is introduced into the intermediatechamber through not less than three piercing holes provided in the upperdie base portion of the upper die, and is further introduced into themolding cavity for filling. On the other hand, deaeration of aerousbodies within the intermediate chamber or molding cavity is performedthrough these piercing holes, whereby these piercing holes concurrentlyserve as introducing holes and deaeration holes of monomer. Since it isnot required to provide any special shielding means or moving mechanismas it was required in the prior art, simplification of the diearrangement is advantageously achieved. Additionally, thanks to thearrangement of not less than three piercing holes around the upper diecolumnar portion of the upper die at equal intervals and supply ofmonomer composition through these holes, supply of monomer compositionis made uniform, while the flowability of the monomer composition of theocular lens components at the time of polymerization shrinkage can beeffectively improved through the presence of the intermediate chamberaround the molding cavity that is filled with monomer composition. Withthis arrangement, ocular lens components can be uniformly supplied intothe molding cavity, whereby surfaces of obtained ocular lens materialcan be made uniform.

According to one preferred embodiment of the device for molding ocularlens material according to the present invention, a covering lid meansis provided as to cover the upper aperture of the hollow hole of thecylindrical main body, whereby the external accumulating chamber formedoutside the upper die base portion of the upper die is shielded from theexterior (atmosphere). The provision of such a covering lid means caneffectively prevent volatilization of monomer at the time ofpolymerization and thus prevent changes in the composition of monomercompositions. In this manner, ocular lens material of uniformcomposition can be advantageously obtained.

According to another preferred embodiment of the device for moldingocular lens materials according to the present invention, a space inwhich aerous bodies might reside is formed between the covering lidmeans and a liquid surface of the monomer composition that isaccumulated in the external accumulating chamber. The presence of suchspace can ease changes in pressure that are caused at the time ofpolymerization, whereby neutralization of polymerization shrinkage canbe more effectively achieved.

The device for molding ocular lens material according to the presentinvention can employ advantageously an arrangement of disposingcylindrical spacers in the hollow hole of the cylindrical main body suchthat they are positioned between the upper die base portion of the upperdie and the lower die base portion of the lower die, so that a distancebetween the upper die molding surface at the tip of the upper diecolumnar portion and the lower die molding surface at the tip of thelower die columnar portion that are opposed with respect to each otheris regulated.

The present invention also relates to a molding method employing theabove described device for molding ocular lens material, in which theabove described molding device according to the present invention isemployed for performing molding of ocular lens or ocular lens materialof shapes corresponding to precursors thereof by polymerizing liquidmonomer compounds of polymer products constituting these articles withina molding cavity, wherein the monomer composition is filled into themolding cavity and intermediate chamber by supplying the monomercomposition into the hollow hole of the cylindrical main body so as tointroduce the monomer composition from the external accumulating chamberto the intermediate chamber through the piercing holes and from theintermediate chamber to the molding cavity through the connectingportion and to accumulate the monomer composition into the externalaccumulating chamber, wherein polymerization process is performed topolymerize the monomer composition residing in the molding cavity,intermediate chamber, and external accumulating chamber to obtain anuniform polymerized object, and wherein the ocular lens material formedin the molding cavity is taken out from the polymerized objectthereafter.

In the method for molding ocular lens material according to the presentinvention, the polymerization process is preferably performed under acondition in which a space in which aerous bodies might reside, morepreferably a closed space parted from the exterior is formed above aliquid surface of the monomer composition accumulated in the externalaccumulating chamber, whereby changes in pressure that are caused at thetime of polymerization might be eased to achieve neutralization ofpolymerization shrinkage in a more effectively manner.

According to another preferred embodiment of the method for moldingocular lens material according to the present invention, theintermediate chamber and molding cavity are maintained at a decompressedcondition after being introduced with the monomer composition andpreceding the polymerization processes, whereby at least bubblesresiding in the molding cavity might be removed to eliminate generationof deficiencies of molding due to the presence of such bubbles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional explanatory view showing an exampleof a device for molding ocular lens material according to the presentinvention;

FIG. 2 is a view of structure of a lower die in the molding device ofFIG. 1 wherein (a) is a half-cut explanatory view of the lower die and(b) an explanatory plan view of the lower die;

FIG. 3 is a view of details of an upper die as employed in FIG. 1wherein (a) is a half-cut explanatory view of the upper die, and (b) anexplanatory bottom view of the upper die;

FIG. 4 is a sectional explanatory view showing flowing forms of thefilled monomer composition in a molding device similarly arranged asthat of FIG. 1;

FIG. 5 is a sectional explanatory view showing arrangements of an uppercovering lid of a die main body arranged in the molding device accordingto the present invention wherein (a) to (d) are all views showingsectional forms of various covering lid members;

FIG. 6 is an explanatory view showing processes from filling the monomercomposition up to polymerization from among mold polymerizationprocesses employing the molding device according to the presentinvention;

FIG. 7 is an explanatory view showing processes in which the monoblockpolymerized object is forcibly pushed out from the die main body afterpolymerization for taking the same out from among mold polymerizationprocesses employing the molding device according to the presentinvention; and

FIG. 8 is an explanatory view showing processes in which an ocular lensmaterial is taken out from the polymerized object that has been takenout in order to finish an intraocular lens from among moldpolymerization processes employing the molding device according to thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The device for molding ocular lens material and the molding methodemploying the same according to the present invention will now beexplained in details with reference to the accompanying drawings.

First, in a molding device according to the present invention as shownin FIG. 1, 2 denotes a cylindrical die main body in which hollow hole 10there is assembled a targeted molding means (molding dies) throughfitting while maintaining a specified remote relationship with respectto each other.

More particularly, a lower die 6 that forms a part of the molding deviceis composed of, as shown in FIG. 1 and FIG. 2, a lower die base portion6 a which assumes a thick, disk-shaped or is columnar, and a columnarlower die columnar portion 6 b that is erected from an upper surface ofthe base portion as to extend upward by a specified length, wherein atip surface of the lower die columnar portion 6 b is formed with a lowerdie molding surface 12 corresponding to one surface of targeted ocularlens material and wherein a periphery of the lower die columnar portion6 b is spaced. Further, as it is clear from FIG. 1, the lower die 6 isliquid-tightly fitted into a lower portion of a hollow hole 4 of the diemain body 2 at its lower die base portion 6 a whereby a lower apertureof the hollow hole 4 is sealed.

On the other hand, an upper die 8 is composed, as shown in FIG. 1 toFIG. 3, of a disc-shaped upper die base portion 8 a and a columnar upperdie columnar portion 8 b that is erected from a lower surface of thebase portion as to extend downward by a specified length, wherein a tipsurface of the upper die columnar portion 8 b is formed with an upperdie molding surface 14 corresponding to another surface of the targetedocular lens material and wherein a periphery of the upper die columnarportion 8 b is spaced.

In addition, eight piercing holes 16 are arranged at the upper die baseportion 8 a of the upper die 8 so as to pierce the same in a verticaldirection and as to be disposed at equal distances around the upper diecolumnar portion 8 b. In order to achieve the purpose of the presentinvention, the number of the piercing holes shall not be less thanthree, since in case of piercing holes less than this value, flowing ofmonomer composition at the time of polymerization shrinkage cannot besufficiently achieved, whereby the transcriptability of the lower diemolding surface 12 or the upper die molding surface 14 becomes poor, andthere might be caused problems that molded surfaces of ocular lensmaterials to be obtained would assume concave or convex portions toresult in uneven shapes of surfaces.

Then, the upper die 8 is so arranged that its upper die columnar portion8 b is fitted into an upper portion of the hollow hole 4 of the die mainbody 2 at its upper die base portion 8 a so that the columnar portionopposes the lower die columnar portion 6 b of the lower die 6, that anintermediate chamber 18 is formed between itself and the lower die baseportion 6 a of the lower die 6 which separates the hollow hole 4 intotwo and into which the monomer composition is filled, and that anexternal containing chamber 20 is formed on a side of an upper apertureof the hollow hole 4 into which the monomer composition is contained. Bythis fitting of the upper die 8, a molding cavity 22 is formed betweenthe lower die molding surface 12 formed at the tip surface of the lowerdie columnar portion 6 b of the opposing lower die 6 and the upper diemolding surface 14 formed at the tip surface of the upper die columnarportion 8 b of the upper die 8 for providing targeted ocular lensmaterial. It should be noted that the thickness of the molding cavity 22in the vertical direction is regulated by a spacer member 10 interposedbetween the lower die 6 and upper die 8, and more particularly, betweenthe lower die base portion 6 a and the upper die base portion 8 a,whereby a communicating portion 24 is formed over the wholecircumference of the molding cavity 22 for communicating the moldingcavity 22 with the intermediate chamber 18 formed around the lower diebase portion 6 a and the upper die base portion 8 a.

Since the molding cavity 22 formed between the lower die base portion 6b of the lower die 6 and the upper die base portion 8 b of the upper die8 provides targeted ocular lens material by polymerization of themonomer composition at this position, it assumes a shape correspondingto such targeted ocular lens material, and in order to provide at leastoptical portions (lens portions) to the ocular lens material, it isgenerally formed to assume a shape corresponding to at least the opticalportion. Therefore, the lower die molding surface 12 or upper diemolding surface 14 that make up the molding cavity 22 are arranged to becapable of at least forming both surfaces of the optical portion of theocular lens material.

Since all of the die main body 2, lower die 6, upper die 8 and thespacer member 10 that constitute the above described molding devicecontact the monomer composition, these might be formed of any materialso long as it is not eroded by such monomer composition. Examplesthereof are fluororesin represented by polytetrafluoroethylene, olefingroup resin such as polypropylene or polyethylene, or polyacetal resin.The material for the die main body 2 might also be metal. Especially,since ocular lens material formed within the molding cavity 22 isgenerally taken out therefrom through cutting a portion of outerdiameter of the accumulated object including the lower die 6 and theupper die 8 as it will be described later, the lower die 6, upper die 8and the spacer member 10 are preferably formed of resin.

Using the molding device arranged as described above, a liquid monomercomposition is filled, as shown in FIG. 4, into the molding cavity 22and the intermediate chamber 18 for providing a polymer productconstituting the ocular lens material, and the monomer composition isalso charged into the external containing chamber 20 for polymerization.Accompanying the polymerization shrinkage that is caused during theprogress of polymerization, the monomer composition 26 within theintermediate chamber 18 is effectively introduced into the moldingcavity 22 through the communicating portion 24, and the monomercomposition 26 within the external communicating chamber 20 into theintermediate chamber 18 through piercing holes 16, respectively, forsupply. Improvements in the flowability of the monomer composition 26,that is, ocular lens component, at the time of polymerization shrinkage,polymer products can be formed with superior transcriptability withinthe molding cavity 22, whereby surfaces of the ocular lens material tobe obtained can be made uniform and free of concave or convex portions.

Moreover, in the above described molding device, since a specifiedamount of monomer composition 26 is sequentially introduced and filledfrom external containing chamber 20 through piercing holes 16 into theintermediate chamber 18, and further through the communicating portion24 to the molding cavity 22, in case volatilization of monomers occursat the time of polymerization, it will only result in compositionalvariations of monomer composition 26 within the external containingchamber 20, whereby influences on monomer composition 26 within theintermediate chamber 18 as well as in the molding cavity 22 can beeffectively restricted. In addition, the piercing holes 16 provided inthe upper die base portion 8 a of the upper die 8 serve as introducingholes of monomer composition and simultaneously, deaeration of aerousbodies within the intermediate chamber 18 or molding cavity 22 isperformed through the piercing holes 16 at the time of introducing themonomer composition. With this arrangement, no special mechanism needsto be provided for the deaeration whereby the die arrangement can besimplified. Further, since the monomer composition 26 within the moldingcavity 22 as well as the monomer composition 26 within the intermediatechamber 18 or external containing chamber 20 are be simultaneouslypolymerized, there is no need to provide any special means for shieldingas it was necessary with conventional mold polymerization methods. Thereis no need to provide for special mechanism such as a moving mechanismfor the molding dies or mechanism for taking out molded articles, it canlargely contribute to simplification of the die arrangement.

In the above described molding device according to the presentinvention, it is preferable that a covering lid means is provided as tocover the upper aperture of the hollow hole 4 of the die main body 2,and further, that a space in which aerous bodies might reside is formedbetween the covering lid means and a liquid surface of the monomercomposition 26 contained in the external containing chamber 20, examplesof which are shown in FIG. 5.

In the example shown in FIG. 5(a), a cap-like covering lid member 28 iscrowned onto an upper end portion of the die main body 2 as a coveringlid means, whereby the upper aperture of the hollow hole 4 is shieldedwith respect to the exterior and whereby a specified space 30 is formedbetween the covering lid member 28 and the liquid surface of the monomercomposition 26 contained in the external containing chamber 20. In theexample shown in FIG. 5(b), a plate-like covering lid member 28 having aspecified thickness is simply mounted on an upper end surface of the diemain body 2, whereby it is also possible to achieve sufficient effectsof the covering lid. It is further effective to place a proper weightonto the covering lid member 28, if required, or to cover the upper endportion of the die main body 2 through a film-like covering lid member28. Further, in the example shown in FIG. 5(c), a covering lid member 28is attached to the upper end portion of the die main body 2 in which itis partially fitted in the hollow hole 4 to shield the upper aperture ofthe hollow hole 4 from the exterior. In the example of FIG. 5(d), acovering lid member 28 of which shape is substantially identical withthat of the hollow hole 4 of the die main body 2 is dropped onto themonomer composition 26 contained in the exterior containing chamber 20of the hollow hole 4 as a lid-dropping arrangement, wherein contact ofthe monomer composition 26 within the exterior containing chamber 20with respect to the exterior atmosphere is intercepted by this coveringlid member 28. It should be noted that the example shown in FIG. 5(d)differs from those shown in the above FIGS. 5(a) to (c) in that no space30 is formed between the covering lid member 28 and the liquid surfaceof the monomer composition 26, but that rather a pressuring force isapplied, as required, to the covering lid member 28 in a direction asindicated by the arrow whereby a specified pressure can be applied tothe monomer composition 26.

In this manner, since the upper aperture of the hollow hole 4 of the diemain body 2 is covered by the covering lid member 28 for shielding theexternal containing chamber 20 from the exterior, volatilization ofmonomer composition 26 contained in the external containing chamber 20at the time of polymerization might be effectively restricted wherebychanges in composition of the monomer composition 26 can be prevented.Thus, the composition of ocular lens material that are polymerized formolding within the molding cavity 22 will not change so that it ispossible to advantageously obtain uniform ocular lens material. Further,through the provision of the space 30 between the liquid surface of themonomer composition 26 and the covering lid member 28, changes inpressure that are caused at the time of polymerization can beeffectively eased through this space 30 whereby polymerization shrinkagecan be neutralized to improve the flowability of the monomer composition26 and uniform supply of monomer composition 26 into the molding cavity22 is enabled. With this arrangement, the transcriptability of the lowerdie molding surface 12 of the lower die columnar portion 6 b and that ofthe upper die molding surface 14 of the upper die columnar portion 8 bthat make up the molding cavity 22 is improved so that the shapes ofobtained ocular lenses can be made uniform. In case no space 30 isprovided, bubbles are easy dispersed within the monomer composition 26at the time of polymerization which are also polymerized as they are sothat lens materials including bubbles therein are apt to be obtained.

The monomer composition 26 that is polymerized in a mold by employingthe molding device according to the present invention arranged as abovedescribed comprises one or more than two types of monomer that are knownin the art for providing polymer products for obtaining ocular lensmaterial. As also known in the art, polymerizing adjuvants such aspolymerization initiators or sensitizers are suitably mixed to themonomer composition 26. The monomer composition 26 is then supplied tothe molding device in a liquid state and is polymerized through knownmethods in a condition in which it is filled as shown in FIG. 4. Just tolist some examples, there might be suitably employed a heatingpolymerization method in which a proper radical polymerization initiatoris mixed to the monomer composition 26 and is gradually heated in atemperature range from room temperature up to approximately 100° C. oran irradiation polymerization method in which polymerization isperformed by irradiating electromagnetic waves such as microwaves,ultraviolet rays or radioactive rays (gamma rays).

In case a heating polymerization method is employed for performingpolymerization, it is effective to raise the temperature step-wise asknown in the art, and the polymerization might alternatively beperformed through bulk polymerization method or a solutionpolymerization method utilizing a solvent or any other knownpolymerization method. A radical polymerization initiator that is addedto the monomer composition 26 for effective progress of thepolymerization might be selected from among azobisisobutyronitrile,azobis dimethylvaleronitrile, benzoyl peroxide, tert-butylhydroperoxide, and cumene hydroperoxide, wherein the radical polymerizationinitiator might be used as a single or in combination of more than twotypes. In case of performing polymerization by employing light rays, itis referable that photo polymerization initiators or sensitizers arefurther added to the monomer composition 26. The mixing amount of suchpolymerization initiators or sensitizers that are added to the monomercomposition 26 is preferably set in the range of approximately 0.002 to10 parts by weight, and more preferably, 0.01 to 2 parts by weight withrespect to 100 parts by weight of the whole polymerization component(whole amount of monomers).

In this manner, at least the lower die 6 and upper die 8 become anuniform connected object through the polymer product obtained bypolymerizing the monomer composition 26 in the molding device, it istaken out from the die main body 2 to be suitably treated by mechanicalprocessing such as cutting or die removing operations so that thetargeted ocular lens material is taken out from the molding cavity 22formed between the lower die molding surface 12 of the lower die 6 andthe upper die molding surface 14 of the upper die 8. In case theobtained ocular lens material assumes a shape of a precursor of anocular lens, the ocular lens material is further mechanically treatedthrough cutting or grinding to obtain an ocular lens having a desiredshape.

In FIGS. 6 to 8, processes for manufacturing an intraocular lensaccording to the present invention are shown, wherein in FIG. 6, thereis employed a molding device 32 formed of a die main body 2 combinedwith a lower die 6 and an upper die 8, and the monomer composition 26 isinjected into the external containing chamber 20 through an injector 34,then introduced to the intermediate chamber 18 through piercing holes 16and finally to the molding cavity 22 through the communicating portion24 for filling the monomer composition 26 into the molding cavity 22 andintermediate chamber 18 and for charging the monomer composition 26 intothe external containing chamber 20. Next, for removing bubbles 36residing in the molding cavity 22, the molding device 32 is housedwithin a vacuum oven 38 to be exposed to decompression whereby thebubbles 36 can be removed from the molding cavity 22. The molding device32 that has undergone decompression is heated (to, for instance,approximately 55° C.) in an heating oven 40 with the upper aperture ofits die main body 2 being covered by covering lid member 28 in order toperform heat polymerization of the filled monomer composition 26,whereby a targeted polymer product 42 is formed within the moldingdevice 32 (see FIG. 7).

After taking out the molding device 32 in which polymerization has beenperformed from the heating oven 40, the uniform object of the lower die6 and the upper die 8 through polymer product 42 is forcibly removedfrom the die main body 2 by using power of a press machine or the likeas shown in FIG. 7. A part of the polymer product 42 that has beenformed in the external containing chamber 20 is removed to obtain anuniform accumulated object 44. As it is evident from the drawings, thisaccumulated object 44 is composed of the lower die 6, upper die 8,spacer member 10 and the polymer product 42.

This uniform accumulated object 44 is chucked by a lathe 46 at a part ofthe lower die 6 and rotated as shown in FIG. 8, a cutting of a portionof outer diameter thereof using a bite 50 is performed while a coolantis sprayed thereon through a cooling spray 48, and cut from the side ofthe upper die 8 so as to reach a part of the molding cavity 22 and so asto be substantially equal to the outer diameter of the upper diecolumnar portion 8 b to obtain an article 52 with a cut outer diameter.The ocular lens material 54 of the article 52 formed in the moldingcavity 22 is formed with holes by using a drill 56, supporting portions58 are attached to the attaching holes formed through the above processand fixed thereto, and by removing the lower die 6 and upper die 8 fromthe ocular lens material 54, the targeted intraocular lens 60 can beobtained.

For removing the ocular lens material 54 from the dies, there might beemployed various methods such as immersing the same into a solution suchas ethanol for swelling and removing, forcibly removing the same, orremoving the same by hardening the ocular lens material 54 throughcooling.

The device for molding ocular lens material and the molding methodemploying the same according to the present invention is not limited tothe above described arrangements and methods alone, and it should beunderstood that anyone with knowledge of the art might performvariation, correction or improvements thereof without departing from thespirit of the present invention.

In the above described example of the molding device, the die main body2 and lower die 6 are separately provided wherein the lower die 6 isfitted to a lower portion of the hollow hole 4 of the die main body 2for closing the lower aperture of the hollow hole 4. The same effectswould be obtained also in an alternative case in which the die main body2 and the lower die 6 are integrally formed. Further, the lower diemolding surface 12 and the upper die molding surface 14 might bothassume shapes of bent concave surfaces, while at least one of them mightbe of a bent convex surface shape. While it is most preferable toperform mutual positioning of the lower die 6 and the upper die 8 byinterposing a spacer member 10 therebetween, it goes without saying thatany alternative arrangement or means might be employed so long as theupper die 8 can be positioned with respect to the lower die 6.

EMBODIMENT

The present invention will further be revealed in details based onseveral embodiments of the present invention, and it should beunderstood that the present invention is not restricted in any way bythe description of these embodiments.

EXAMPLE 1

Employing a molding device as shown in FIG. 1 (it should be noted thateight piercing holes 16 are arranged at equal intervals in acircumferential direction of the upper die base portion 8 a of the upperdie 8), an ocular lens material 54 for providing an optical portion ofintraocular lens 60 was manufactured in accordance with manufacturingprocesses as shown in FIGS. 6 to 8.

More particularly, a monomer composition 26 was prepared by using 70parts by weight of phenoxy ethyl acrylate, 30 parts by weight of ethylacrylate, 20 parts by weight of 2-hydroxyethyl metacrylate, 4 parts byweight of butanediol diacrylate as a cross linking agent and 0.83 partsby weight of 2,2′-azobis(2,4-dimethylvaleronitrile) as a radicalpolymerization initiator. This was supplied to the external containingchamber 20 of the molding device 32, then introduced into theintermediate chamber 18 through piercing holes 16 and further introducedinto the molding cavity 22 through the communicating portion 24 andfilled therein, vacuum deaerated in the vacuum oven 38, maintained inthe heating oven 40 for 16 hours at 60° C., and gradually raised intemperature over 4 hours from 60 to 100° C. whereby mold polymerizationof the monomer composition 26 was performed to generate a polymerproduct 42 within the molding device 32.

Thereafter, the uniform accumulated object 44 including the lower die 6and the upper die 8 was forcibly pushed out from the die main body 2 byusing a hydraulic press, and by cutting a portion of outer diameter withthe bite 50, an article 52 with a cut outer diameter was obtained. Theocular lens material 54 formed in the molding cavity 22 for providing anoptical portion of the intraocular lens was provided with holes andattached with supporting portions 58, and removing of the lower die 6and upper die columnar portion 8 b was performed through immersion intoethanol. It should be noted that this removing operation of the diescould be easily performed and the optical portion of the obtainedintraocular lens 60 assumed uniform surfaces corresponding to those ofthe lower die molding surface 12 and the upper die molding surface 14and presented favorable transcriptability.

EXAMPLE 2

Polymerization of monomer composition 26 in a mold was similarlyperformed under the same conditions as Example 1 except for the pointthat the number of piercing holes 16 provided in the upper die baseportion 8 a of the upper die 8 was set to be four (wherein these arearranged in the circumferential direction at phase differences of 90°),and the uniform accumulated product 44 thus obtained was processed intothe targeted intraocular lens 60.

It was found that removing of the lower die 6 and upper die 8 (moreparticularly, the upper die columnar portion 8 b) from the uniformaccumulated product 44 could be easily performed while maintaining afavorable shape of the lens. Moreover, the optical portion of theobtained uniform intraocular lens 60 assumed a desired shape, favorabletranscriptability, and was coincident with the shape of the lower diemolding surface 12 and the upper die molding surface 14, and was free ofdrawbacks related to compositional changes owing to volatilization ofmonomers.

COMPARATIVE EXAMPLE 1

Polymerization of monomer composition 26 in a mold was performed underthe same conditions as Example 1 except for the point that the number ofthe piercing hole 16 was set to one, and the optical lens material 54was formed within the molding cavity 22 formed between the lower diemolding surface 12 of the lower die 6 and the upper die molding surface14 of the upper die 8. The ocular lens material 54 thus obtained assumednot uniform surfaces that were different from desirable shapescorresponding to the lower die molding surface 12 or the upper diemolding surface 14 and presented remarkable concave and convex portions.

COMPARATIVE EXAMPLE 2

Polymerization of monomer composition 26 in a mold was performed underthe same conditions as Example 1 except for the point that two piercingholes 16 were provided at a phase difference of 180°, and the targetedocular lens material (optical portion of the intraocular lens) 54 wasformed. It was found that the ocular lens material 54 thus obtainedassumed not uniform surfaces that were different from desirable shapescorresponding to the lower die molding surface 12 or the upper diemolding surface 14 and presented concave and convex portions.

As it is evident from comparison of the above Examples 1, 2 andComparative Examples 1, 2, the molding device 32 of the presentinvention provided with not less than three piercing holes 16 wascapable of producing ocular lens materials 54 of favorabletranscriptability despite of its simple die arrangement. It isconsidered that such favorable results could be obtained in thearrangement of the molding device according to Examples 1 and 2 sincethe monomer composition 26 is effectively supplied to the intermediatechamber 18 or molding cavity 22 from the side of the external containingchamber 20 after the introduction of the monomer composition 26 andsince uniform flowing is caused. On the other hand, in case only one ortwo piercing holes are provided as in Comparative Examples 1 and 2, thesupply of monomer composition 26 to the intermediate chamber 18 andmolding cavity 22 is not uniform which resulted in surfaces of theobtained ocular lens materials 54 that were not uniform and poortranscriptability. It is assumed that this was because the flow ofmonomer composition 26 to the intermediate chamber 18 and molding cavity22 was not uniform.

The ocular lens materials (optical portions) 54 obtained in the aboveExamples 1, 2 and Comparative Examples 1, 2 were measured for theirrefracting power (diopter: D) by using a principal point refractingpower measuring device through magnification method, measured for theirresolution as regulated by the approved standard for intraocular lenses(Ministry of Health and Welfare, May 10, 1985, PAB (PharmaceuticalAffairs Bureau) Notification No. 489), and the resolution U (number/mm)was obtained based on the equation U=(D·d/λ)×10³×0.6 (note that Ddenotes a refraction coefficient in air, d an effective diameter of thelens (3 mm), λ a wavelength of light employed for the measurement (Hg, eline: 546.1 mm)), and respective results are indicated in the Table 1below. As it is quite evident from this Table 1, the ocular lensmaterials obtained in the Examples 1 and 2 according to the invention isremarkably superior in terms of resolution as compared to those obtainedin Comparative Examples 1, 2.

TABLE 1 Refracting Power: D Resolution: U (diopter) (number/mm) Example1 62.2 280 Example 2 63.7 225 Comparative N.A. N.A. Example 1Comparative 63.2 160 Example 2

As it is evident from the above description, simplification of the diearrangement of the molding device for molding ocular lens materialsthrough polymerization in a mold can be effectively achieved in thepresent invention, and the flowability of monomer composition at thetime of polymerization shrinkage can be effectively improved whereby themonomer composition can be uniformly supplied into the molding cavity toresult in ocular lens materials of uniform surfaces, and in ocular lensmaterials having precise surfaces corresponding to the molding surfaceswhereby the transcriptability can be remarkably improved.

INDUSTRIAL APPLICABILITY

The molding device and molding method according to the present inventionis useful as having a simplified die arrangement, wherein improvementsin flowability of the monomer composition of the ocular lens componentat the time of polymerization shrinkage and uniform supply of suchmonomer composition into the molding cavity that have been enabled inthe present invention result in high transcriptability of the moldingcavity interior (molding surface), whereby surfaces of ocular lensmaterial to be obtained can be made uniform.

What is claimed is:
 1. A device for molding ocular lens material whichis a device for molding ocular lens or ocular lens material bypolymerizing liquid monomer composition of polymer products constitutingthese articles within a molding cavity, the device comprises: acylindrical main body having a hollow hole in which the monomercomposition is accumulated; a lower die composed of a lower die baseportion disposed in a lower portion of the hollow hole to close thelower portion of the hollow hole of the cylindrical main body, and alower die columnar portion that is erected to extend upward from anupper surface of the lower die base portion within the hollow hole, asurface at a top of the lower die columnar portion being formed with alower die molding surface corresponding to one surface of the ocularlens material; an upper die composed of an upper die base portion thatis fitted into an upper portion of the hollow hole of the cylindricalmain body, forming an intermediate chamber between the upper die baseportion and the lower die base portion of the lower die into which themonomer composition is filled, and forming an external accumulatingchamber on a side of an upper portion of the hollow hole into which themonomer composition is accumulated, and an upper die columnar portionthat is erected to extend downward from a lower surface of the upper diebase portion within the hollow hole, a surface at a top of the upper diecolumnar portion being formed with an upper die molding surfacecorresponding to another surface of the ocular lens material, wherein aperiphery of the upper die columnar portion is spaced from the lower diecolumnar portion of the lower die, wherein a molding cavity is formedbetween the upper die molding surface of the upper die columnar portionand the lower die molding surface of the lower die columnar portion, andwherein a communicating portion is formed over a whole circumference ofan exterior circumferential portion of the molding cavity through whichthe monomer composition is introduced from the intermediate chamber tothe molding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portion. 2.The device of claim 1, wherein a covering lid means is provided to coverthe upper portion of the hollow hole of the cylindrical main body. 3.The device of claim 2, wherein a space is formed between the coveringlid means and a liquid surface of the monomer composition that isaccumulated in the external accumulating chamber.
 4. The device of claim3, wherein cylindrical spacers are disposed in the hollow hole of thecylindrical main body such that they are positioned between the upperdie base portion of the upper die and the lower die base portion of thelower die, so that a distance between the upper die molding surface atthe tip of the upper die columnar portion and the lower die moldingsurface at the tip of the lower die columnar portion that are opposedwith respect to each other is regulated.
 5. A method for molding ocularlens material, comprising the steps of: providing a device for moldingocular lens material which is a device for molding ocular lens or ocularlens material by polymerizing liquid monomer composition of polymerproducts constituting these articles within a molding cavity, the devicecomprises: a cylindrical main body having a hollow hole in which themonomer composition is accumulated; a lower die composed of a lower diebase portion disposed in a lower portion of the hollow hole to close thelower portion of the hollow hole of the cylindrical main body, and alower die columnar portion that is erected to extend upward from anupper surface of the lower die base portion within the hollow hole, asurface at a top of the lower die columnar portion being formed with alower die molding surface corresponding to one surface of the ocularlens material; an upper die composed of an upper die base portion thatis fitted into an upper portion of the hollow hole of the cylindricalmain body, forming an intermediate chamber between the upper die baseportion and the lower die base portion of the lower die into which themonomer composition is filled, and forming an exterior accumulatingchamber on a side of an upper portion of the hollow hole into which themonomer composition is accumulated, and an upper die columnar portionthat is erected to extend downward from a lower surface of the upper diebase portion within the hollow hole, a surface at a top of the upper diecolumnar portion being formed with an upper die molding surfacecorresponding to another surface of the ocular lens material, wherein aperiphery of the upper die columnar portion is spaced from the lower diecolumnar portion of the lower die, wherein a molding cavity is formedbetween the upper die molding surface of the upper die columnar portionand the lower die molding surface of the lower die columnar portion, andwherein a communicating portion is formed over a whole circumference ofan exterior circumferential portion of the molding cavity through whichthe monomer composition is introduced from the intermediate chamber tothe molding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portion,wherein a covering lid means is provided to cover the upper portion ofthe hollow hole of the cylindrical main body, wherein a space in whichair bubbles reside is formed between the covering lid means and a liquidsurface of the monomer composition that is accumulated in the externalaccumulating chamber, wherein cylindrical spacers are disposed in thehollow hole of the cylindrical main body such that they are positionedbetween the upper die base portion of the upper die and the lower diebase portion of the lower die, so that a distance between the upper diemolding surface at the top of the upper die columnar portion and thelower die molding surface at the top of the lower die columnar portionthat are opposed with respect to each other is regulated; filling themonomer composition into the molding cavity and intermediate chamber bysupplying the monomer composition into the hollow hole of thecylindrical main body so as to introduce the monomer composition fromthe external accumulating chamber to the intermediate chamber throughthe piercing holes and from the intermediate chamber to the moldingcavity through the communicating portion and to accumulate the monomercomposition into the external accumulating chamber; polymerizing themonomer composition residing in the molding cavity, intermediatechamber, and external accumulating chamber to obtain an uniformpolymerized object; and taking out the ocular lens material formed inthe molding cavity from the polymerized object thereafter.
 6. The methodof claim 5, wherein the polymerizing step is performed under a conditionin which a space in which air bubbles reside is formed above a liquidsurface of the monomer composition accumulated in the externalaccumulating chamber.
 7. The method of claim 6, wherein the intermediatechamber and molding cavity are maintained at a decompressed conditionafter being introduced with the monomer composition and preceding thepolymerizing step, whereby at least bubbles residing in the moldingcavity are removed to eliminate generation of deficiencies of moldingdue to the presence of such bubbles.
 8. The method of claim 5, whereinthe intermediate chamber and molding cavity are maintained at adecompressed condition after being introduced with the monomercomposition and preceding the polymerizing step, whereby at leastbubbles residing in the molding cavity are removed to eliminategeneration of deficiencies of molding due to the presence of suchbubbles.
 9. The device of claim 1, wherein cylindrical spacers aredisposed in the hollow hole of the cylindrical main body such that theyare positioned between the upper die base portion of the upper die andthe lower die base portion of the lower die, so that a distance betweenthe upper die molding surface at the tip of the upper die columnarportion and the lower die molding surface at the top of the lower diecolumnar portion that are opposed with respect to each other isregulated.
 10. A method for molding ocular lens material, comprising thesteps of: providing a device for molding ocular lens material which is adevice for molding ocular lens or ocular lens material by polymerizingliquid monomer composition of polymer products constituting thesearticles within a molding cavity, the device comprises: a cylindricalmain body having a hollow hole in which the monomer composition isaccumulated; a lower die composed of a lower die base portion disposedin a lower portion of the hollow hole to close the lower portion of thehollow hole of the cylindrical main body, and a lower die columnarportion that is erected to extend upward from an upper surface of thelower die base portion within the hollow hole, a surface at a top of thelower die columnar portion being formed with a lower die molding surfacecorresponding to one surface of the ocular lens material; an upper diecomposed of a upper die base portion that is fitted into an upperportion of the hollow hole of the cylindrical main body, forming anintermediate chamber between the upper die base portion and the lowerdie base portion of the lower die into which the monomer composition isfilled, and forming an exterior accumulating chamber on a side of anupper portion of the hollow hole into which the monomer composition isaccumulated, and an upper die columnar portion that is erected to extenddownward from a lower surface of the upper die base portion within thehollow hole, a surface at a top of the upper die columnar portion beingformed with an upper die molding surface corresponding to anothersurface of the ocular lens material, wherein a periphery of the upperdie columnar portion is spaced from the lower die columnar portion ofthe lower die, wherein a molding cavity is formed between the upper diemolding surface of the upper die columnar portion and the lower diemolding surface of the lower die columnar portion, and wherein acommunicating portion is formed over a whole circumference of anexterior circumferential portion of the molding cavity through which themonomer composition is introduced from the intermediate chamber to themolding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portionwherein cylindrical spacers are disposed in the hollow hole of thecylindrical main body such that they are positioned between the upperdie base portion of the upper die and the lower die base portion of thelower die, so that a distance between the upper die molding surface atthe top of the upper die columnar portion and the lower die moldingsurface at the top of the lower die columnar portion that are opposedwith respect to each other is regulated; filling the monomer compositioninto the molding cavity and intermediate chamber by supplying themonomer composition into the hollow hole of the cylindrical main body soas to introduce the monomer composition from the external accumulatingchamber to the intermediate chamber through the piercing holes and fromthe intermediate chamber to the molding cavity through the communicatingportion and to accumulate the monomer composition into the externalaccumulating chamber; polymerizing the monomer composition residing inthe molding cavity, intermediate chamber, and external accumulatingchamber to obtain an uniform polymerized object; and taking out theocular lens material formed in the molding cavity from the polymerizedobject thereafter.
 11. The method of claim 10, wherein the polymerizingstep is performed under a condition in which a space in which airbubbles reside is formed above a liquid surface of the monomercomposition accumulated in the external accumulating chamber.
 12. Themethod of claim 11, wherein the intermediate chamber and molding cavityare maintained at a decompressed condition after being introduced withthe monomer composition and preceding the polymerizing step, whereby atleast bubbles residing in the molding cavity are removed to eliminategeneration of deficiencies of molding due to the presence of suchbubbles.
 13. The method of claim 10, wherein the intermediate chamberand molding cavity are maintained at a decompressed condition afterbeing introduced with the monomer composition and preceding thepolymerizing step, whereby at least bubbles residing in the moldingcavity are removed to eliminate generation of deficiencies of moldingdue to the presence of such bubbles.
 14. The device of claim 2, whereincylindrical spacers are disposed in the hollow hole of the cylindricalmain body such that they are positioned between the upper die baseportion of the upper die and the lower die base portion of the lowerdie, so that a distance between the upper die molding surface at the topof the upper die columnar portion and the lower die molding surface atthe top of the lower die columnar portion that are opposed with respectto each other is regulated.
 15. A method for molding ocular lensmaterial, comprising the steps of: providing a device for molding ocularlens material which is a device for molding ocular lens or ocular lensmaterial by polymerizing liquid monomer composition of polymer productsconstituting these articles within a molding cavity, the devicecomprises: a cylindrical main body having a hollow hole in which themonomer composition is accumulated; a lower die composed of a lower diebase portion disposed in a lower portion of the hollow hole to close thelower portion of the hollow hole of the cylindrical main body, and alower die columnar portion that is erected to extend upward from anupper surface of the lower die base portion within the hollow hole, asurface at a top of the lower die columnar portion being formed with alower die molding surface corresponding to one surface of the ocularlens material; an upper die composed of a upper die base portion that isfitted into an upper portion of the hollow hole of the cylindrical mainbody, forming an intermediate chamber between the upper die base portionand the lower die base portion of the lower die into which the monomercomposition is filled, and forming an exterior accumulating chamber on aside of an upper portion of the hollow hole into which the monomercomposition is accumulated, and an upper die columnar portion that iserected to extend downward from a lower surface of the upper die baseportion within the hollow hole, a surface at a top of the upper diecolumnar portion being formed with an upper die molding surfacecorresponding to another surface of the ocular lens material, wherein aperiphery of the upper die columnar portion is spaced from the lower diecolumnar portion of the lower die, wherein a molding cavity is formedbetween the upper die molding surface of the upper die columnar portionand the lower die molding surface of the lower die columnar portion, andwherein a communicating portion is formed over a whole circumference ofan exterior circumferential portion of the molding cavity through whichthe monomer composition is introduced from the intermediate chamber tothe molding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portionwherein a covering lid means is provided to cover the upper portion ofthe hollow hole of the cylindrical main body, wherein cylindricalspacers are disposed in the hollow hole of the cylindrical main bodysuch that they are positioned between the upper die base portion of theupper die and the lower die base portion of the lower die, so that adistance between the upper die molding surface at the top of the upperdie columnar portion and the lower die molding surface at the top of thelower die columnar portion that are opposed with respect to each otheris regulated; filling the monomer composition into the molding cavityand intermediate chamber by supplying the monomer composition into thehollow hole of the cylindrical main body so as to introduce the monomercomposition from the external accumulating chamber to the intermediatechamber through the piercing holes and from the intermediate chamber tothe molding cavity through the communicating portion and to accumulatethe monomer composition into the external accumulating chamber;polymerizing the monomer composition residing in the molding cavity,intermediate chamber, and external accumulating chamber to obtain anuniform polymerized object; and taking out the ocular lens materialformed in the molding cavity from the polymerized object thereafter. 16.The method of claim 15, wherein the polymerizing step is performed undera condition in which a space in which air bubbles reside is formed abovea liquid surface of the monomer composition accumulated in the externalaccumulating chamber.
 17. The method of claim 16, wherein theintermediate chamber and molding cavity are maintained at a decompressedcondition after being introduced with the monomer composition andpreceding the polymerizing step, whereby at least bubbles residing inthe molding cavity are removed to eliminate generation of deficienciesof molding due to the presence of such bubbles.
 18. The method of claim15, wherein the intermediate chamber and molding cavity are maintainedat a decompressed condition after being introduced with the monomercomposition and preceding the polymerizing step, whereby at leastbubbles residing in the molding cavity are removed to eliminategeneration of deficiencies of molding due to the presence of suchbubbles.
 19. A method for molding ocular lens material, comprising thesteps of: providing a device for molding ocular lens material which is adevice for molding ocular lens or ocular lens material by polymerizingliquid monomer composition of polymer products constituting thesearticles within a molding cavity the device comprises: a cylindricalmain body having a hollow hole in which the monomer composition isaccumulated; a lower die composed of a lower die base portion disposedin a lower portion of the hollow hole to close the lower portion of thehollow hole of the cylindrical main body, and a lower die columnarportion that is erected to extend upward from an upper surface of thelower die base portion within the hollow hole, a surface at a top of thelower die columnar portion being formed with a lower die molding surfacecorresponding to one surface of the ocular lens material; an upper diecomposed of a upper die base portion that is fitted into an upperportion of the hollow hole of the cylindrical main body, forming anintermediate chamber between the upper die base portion and the lowerdie base portion of the lower die into which the monomer composition isfilled, and forming an exterior accumulating chamber on a side of anupper portion of the hollow hole into which the monomer composition isaccumulated, and an upper die columnar portion that is erected to extenddownward from a lower surface of the upper die base portion within thehollow hole, a surface at a top of the upper die columnar portion beingformed with an upper die molding surface corresponding to anothersurface of the ocular lens material, wherein a periphery of the upperdie columnar portion is spaced from the lower die columnar portion ofthe lower die, wherein a molding cavity is formed between the upper diemolding surface of the upper die columnar portion and the lower diemolding surface of the lower die columnar portion and wherein acommunicating portion is formed over a whole circumference of anexterior circumferential portion of the molding cavity through which themonomer composition is introduced from the intermediate chamber to themolding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portion,wherein a covering lid means is provided to cover the upper portion ofthe hollow hole of the cylindrical main body; filling the monomercomposition into the molding cavity and intermediate chamber bysupplying the monomer composition into the hollow hole of thecylindrical main body so as to introduce the monomer composition fromthe external accumulating chamber to the intermediate chamber throughthe piercing holes and from the intermediate chamber to the moldingcavity through the communicating portion and to accumulate the monomercomposition into the external accumulating chamber; polymerizing themonomer composition residing in the molding cavity, intermediatechamber, and external accumulating chamber to obtain an uniformpolymerized object; and taking out the ocular lens material formed inthe molding cavity from the polymerized object thereafter.
 20. Themethod of claim 19, wherein the polymerizing step is performed under acondition in which a space in which air bubbles reside is formed above aliquid surface of the monomer composition accumulated in the externalaccumulating chamber.
 21. The method of claim 20, wherein theintermediate chamber and molding cavity are maintained at a decompressedcondition after being introduced with the monomer composition andpreceding the polymerizing step, whereby at least bubbles residing inthe molding cavity are removed to eliminate generation of deficienciesof molding due to the presence of such bubbles.
 22. The method of claim19, wherein the intermediate chamber and molding cavity are maintainedat a decompressed condition after being introduced with the monomercomposition and preceding the polymerizing step, whereby at leastbubbles residing in the molding cavity are removed to eliminategeneration of deficiencies of molding due to the presence of suchbubbles.
 23. A method for molding ocular lens material, comprising thesteps of: providing a device for molding ocular lens material which is adevice for molding ocular lens or ocular lens material by polymerizingliquid monomer composition of polymer products constituting thesearticles within a molding cavity, the device comprises: a cylindricalmain body having a hollow hole in which the monomer composition isaccumulated; a lower die composed of a lower die base portion disposedin a lower portion of the hollow hole to close the lower portion of thehollow hole of the cylindrical main body, and a lower die columnarportion that is erected to extend upward from an upper surface of thelower die base portion within the hollow hole, a surface at a top of thelower die columnar portion being formed with a lower die molding surfacecorresponding to one surface of the ocular lens material; an upper diecomposed of a upper die base portion that is fitted into an upperportion of the hollow hole of the cylindrical main body, forming anintermediate chamber between the upper die base portion and the lowerdie base portion of the lower die into which the monomer composition isfilled, and forming an exterior accumulating chamber on a side of anupper portion of the hollow hole into which the monomer composition isaccumulated, and an upper die columnar portion that is erected to extenddownward from a lower surface of the upper die base portion within thehollow hole, a surface at a top of the upper die columnar portion beingformed with an upper die molding surface corresponding to anothersurface of the ocular lens material, wherein a periphery of the upperdie columnar portion is spaced from the lower die columnar portion ofthe lower die, wherein a molding cavity is formed between the upper diemolding surface of the upper die columnar portion and the lower diemolding surface of the lower die columnar portion, and wherein acommunicating portion is formed over a whole circumference of anexterior circumferential portion of the molding cavity through which themonomer composition is introduced from the intermediate chamber to themolding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portion;filling the monomer composition into the molding cavity and intermediatechamber by supplying the monomer composition into the hollow hole of thecylindrical main body so as to introduce the monomer composition fromthe external accumulating chamber to the intermediate chamber throughthe piercing holes and from the intermediate chamber to the moldingcavity through the communicating portion and to accumulate the monomercomposition into the external accumulating chamber; polymerizing themonomer composition residing in the molding cavity, intermediatechamber, and external accumulating chamber to obtain an uniformpolymerized object; and taking out the ocular lens material formed inthe molding cavity from the polymerized object thereafter.
 24. Themethod of claim 23, wherein the polymerizing step is performed under acondition in which a space in which air bubbles reside is formed above aliquid surface of the monomer composition accumulated in the externalaccumulating chamber.
 25. The method of claim 24, wherein theintermediate chamber and molding cavity are maintained at a decompressedcondition after being introduced with the monomer composition andpreceding the polymerizing step, whereby at least bubbles residing inthe molding cavity are removed to eliminate generation of deficienciesof molding due to the presence of such bubbles.
 26. The method of claim23, wherein the intermediate chamber and molding cavity are maintainedat a decompressed condition after being introduced with the monomercomposition and preceding the polymerizing step, whereby at leastbubbles residing in the molding cavity are removed to eliminategeneration of deficiencies of molding due to the presence of suchbubbles.
 27. A method for molding ocular lens material, comprising thesteps of: providing a device for molding ocular lens material which is adevice for molding ocular lens or ocular lens material by polymerizingliquid monomer composition of polymer products constituting thesearticles within a molding cavity, the device comprises: a cylindricalmain body having a hollow hole in which the monomer composition isaccumulated; a lower die composed of a lower die base portion disposedin a lower portion of the hollow hole to close the lower portion of thehollow hole of the cylindrical main body, and a lower die columnarportion that is erected to extend upward from an upper surface of thelower die base portion within the hollow hole, a surface at a top of thelower die columnar portion being formed with a lower die molding surfacecorresponding to one surface of the ocular lens material; an upper diecomposed of a upper die base portion that is fitted into an upperportion of the hollow hole of the cylindrical main body, forming anintermediate chamber between the upper die base portion and the lowerdie base portion of the lower die into which the monomer composition isfilled, and forming an exterior accumulating chamber on a side of anupper portion of the hollow hole into which the monomer composition isaccumulated, and an upper die columnar portion that is erected to extenddownward from a lower surface of the upper die base portion within thehollow hole, a surface at a top of the upper die columnar portion beingformed with an upper die molding surface corresponding to anothersurface of the ocular lens material, wherein a periphery of the upperdie columnar portion is spaced from the lower die columnar portion ofthe lower die, wherein a molding cavity is formed between the upper diemolding surface of the upper die columnar portion and the lower diemolding surface of the lower die columnar portion, and wherein acommunicating portion is formed over a whole circumference of anexterior circumferential portion of the molding cavity through which themonomer composition is introduced from the intermediate chamber to themolding cavity, wherein not less than three piercing holes forintroducing the monomer composition from the external accumulatingchamber to the intermediate chamber are provided to pierce the upper diebase portion of the upper die in a vertical direction and to bepositioned at equal intervals around the upper die columnar portion,wherein a covering lid means is provided to cover the upper portion ofthe hollow hole of the cylindrical main body, wherein a space in whichair bubbles reside is formed between the covering lid means and liquidsurface of the monomer composition that is accumulated in the externalaccumulating chamber; filling the monomer composition into the moldingcavity and intermediate chamber by supplying the monomer compositioninto the hollow hole of the cylindrical main body so as to introduce themonomer composition from the external accumulating chamber to theintermediate chamber through the piercing holes and from theintermediate chamber to the molding cavity through the communicatingportion and to accumulate the monomer composition into the externalaccumulating chamber; polymerizing the monomer composition residing inthe molding cavity, intermediate chamber, and external accumulatingchamber to obtain an uniform polymerized object; and taking out theocular lens material formed in the molding cavity from the polymerizedobject thereafter.
 28. The method of claim 27, wherein the polymerizingstep is performed under a condition in which a space in which airbubbles reside is formed above a liquid surface of the monomercomposition accumulated in the external accumulating chamber.
 29. Themethod of claim 28, wherein the intermediate chamber and molding cavityare maintained at a decompressed condition after being introduced withthe monomer composition and preceding the polymerizing step, whereby atleast bubbles residing in the molding cavity are removed to eliminategeneration of deficiencies of molding due to the presence of suchbubbles.
 30. The method of claim 27, wherein the intermediate chamberand molding cavity are maintained at a decompressed condition afterbeing introduced with the monomer composition and preceding thepolymerizing step, whereby at least bubbles residing in the moldingcavity are removed to eliminate generation of deficiencies of moldingdue to the presence of such bubbles.